Assessment of parents´ knowledge regarding phenylketonuria and its affecting factors: a cross-sectional study

Introduction the management of phenylketonuria (PKU) is complex. Practical skills and knowledge of individuals taking care of PKU patients are important for treatment compliance. This study investigated parents´ knowledge about PKU and its affecting factors. The study group consisted of 62 parents of PKU patients. Methods data were collected using a ready-made questionnaire on sociodemographic characteristics, PKU and dietary treatment. Total knowledge score (KS) was calculated by giving 5 points for each correct answer. Results the study included 34 mothers and 28 fathers; 90.3% of patients were diagnosed during the newborn screening program, 6.5% between ages 1 and 2, and 3.2% at age 6 or after. Among all, 38.7% presented to their follow-up appointments with their mothers, 61.3% with both their parents and none with their father alone. Mothers answered all questions more accurately than fathers. Mothers´ and fathers´ mean KSs were 73.97 ± 12.72 and 53.04 ± 22.25, respectively. The highest KS was obtained among parents whose children were 13 years of age or older. Conclusion the presence of another family member, parents´ education level, working status and professional qualifications, previous training on PKU and family´s economic status were the affecting factors. Creating a PKU dietary plan requires knowledge and diligence. Patients and their parents should be periodically informed about the disease and dietary treatment in order to increase their level of knowledge.


Introduction
Phenylketonuria (PKU) is an inherited metabolic disorder caused by a deficiency of phenylalanine (Phe) hydroxylase activity. This disease shows an autosomal recessive transition and constitutes the most common inherited disorder of amino acid metabolism [1,2]. A high incidence is reported in Turkey due to high consanguinity within the population. While the incidence is generally 1/10000-15000 live births, it is even higher in Turkey (1/4000-5000 live births) [3,4]. Neurological problems such as mental impairment, behavioral problems, epilepsy, and mental retardation may occur due to increased Phe levels in patients with late diagnoses [5]. Newborn screening programs could identify the children with PKU as early as possible, and the most crucial consequence of the disease, mental motor retardation, could be prevented with appropriate treatment. In the 1950s, Bickel and colleagues [6] reported that a Phe-restricted diet gives patients a chance of normal life and allows normal brain development. When a specific Phe-restricted diet and other necessary treatments, such as micronutrient supplementation, are started, symptoms begin to diminish [7]. Children with PKU who properly manage their diet usually do not show any complaints and grow normally. However, the desirable outcome would not always be achieved. Therefore, factors affecting development and diet compliance have been sought since the 1950s [8,9].
Applying a limited diet is quite difficult due to intensive diet training, self-confidence, and selfsufficiency requirements. Dietary compliance of patients with PKU is completely under parental supervision throughout infancy. In childhood, parents play a significant role in diet adaptation and nutrient selection [10]. Caring for these children requires great attention and effort. Therefore, parents´ motivations, good understanding, and organizing and accepting the diet are vital factors for the surveillance of the diet [11]. Therefore, the management of children with PKU should be ensured by their families, nutritionists, and metabolic specialists [12]. The effect of knowledge and skills of PKU patients and their parents on diet perception cannot be underestimated. It is necessary to give regular training to patients and their parents about disease and diet to control the dietary intake and to ensure their adaptation to dietary treatments [13]. There are few studies on the effect of parent and patient knowledge on nutritional compliance and the treatment of PKU. Therefore, this study aimed to evaluate the knowledge levels of the parents of children with PKU residing in Anatolia, Turkey.

Data collection
After providing detailed information about the study, signed informed consent was obtained from parents. The data were obtained by filling out a questionnaire with a face-to-face interview technique. In the second stage, the parents were informed about completing the research scale to be used in the study, and they did under the supervision of the researcher. The questionnaire was prepared by the researcher after a comprehensive literature review, having 10 questions on sociodemographic characteristics and 20 questions on PKU disease and diet. The questions on knowledge were based on the textbook Classical Pediatrics by Nelson [14], and the correct and incorrect answers were evaluated according to the information given in this textbook. The total knowledge level score (KLS) was calculated by giving 5 points for each correct answer and was given between 0 and 100 points (quantitative variables).

Statistical analysis
The data were transferred to a computer with the SPSS 16.0 program (USA). Descriptive statistical analyses were performed. The values are presented as mean ± SD or median (min-max) and number (percentage). The distribution normality was tested using the Shapiro-Wilk test. The comparisons between continuous data were made with the Mann-Whitney U test, and the comparisons between categorical data were performed using the Chi-square test and Fisher exact test where applicable. A p-value of < 0.05 was considered statistically significant.

Results
A total of 34 mothers (27.4%) and 28 fathers (22.6%) were included in the study. The mean ages of mothers, fathers, and children were 34.53 ± 7.22, 37.21 ± 6.27, and 9.65 ± 4.92 years, respectively (Table 1). More than 45% of the parents had less than 8 years of schooling. As the family´s socioeconomic status was concerned, more than 75% of the 62 parents described their family´s economic conditions as poor and/or average (Table 1). Among all, 46.8% of the parents were found to be married to relatives. Also, 56 (90.3%) children were diagnosed during the newborn screening program, 4 (6.5%) children were diagnosed between 1-2 years of age, and 2 children (3.2%) had the diagnosis at ages 6 years or more, and 87.1% of the families did not have any other children with PKU. To the question "Does your child go to controls regularly?" 17.7% (11/62) of the parents answered "No and/or from time to time." It was learned that 61.3% (n = 38) of the children went to controls both with their mothers and fathers, 38.7% (n = 24) only with their mothers, and none only with their fathers.
Among all, 48 parents (77.4%) stated that they had received some training on PKU and/or PKU diets (Table 2). Surprisingly, 14.5% (n = 9) of the parents did not know what medication their children were taking. Overall, maternal knowledge on most aspects of PKU and its diet was better than the fathers´. Mothers answered all questions more accurately than fathers, but the statistical difference was not significant (p > 0.05) ( Table 3). On the other hand, the answer difference between the mothers and the fathers for the questions on PKU diet was more evident. The mothers´ correct answer rates were higher than fathers´ in all questions (Table 3). When we compared the answers of parents, the biggest difference between the mothers and fathers was observed in questions related to PKU diet, such as "Can breast milk be given to the baby with PKU?" How many meals should a child with PKU be fed? and "Which of the following foods can be consumed instead of bread?"

Knowledge level score
KLSs according to the sociodemographic characteristics of the parents are shown in Table 3. Mothers´ and fathers´ mean KLSs were 73.97 ± 12.72 and 53.04 ± 22.25, respectively, and the difference was statistically significant (p < 0.05). When compared with children´s age, the highest KLS was obtained among the parents whose children were 13 years or more. KLSs showed a significant difference among the education levels of parents, so the KLSs of the primary school group were significantly lower than those of the other groups (p < 0.05). The KLSs of those who had previously received training on PKU and its diet were significantly higher than those of the parents who had not received any (75 ± 13.19 vs. 35 ± 10.74, respectively, p < 0.05). Mothers and fathers who were going to controls together showed higher KLSs than only mothers who went to controls (p < 0.05). Parents having more than one PKU patient at home showed higher KLSs than those who did not (75.63 ± 17.61 and 62.87 ± 20.43, respectively, p > 0.05).

Discussion
Results of this study revealed that parents´ knowledge of the general issues of PKU was nearly perfect. However, when it accounted for the dietrelated questions, the knowledge fell sharply (Table 3). For example, the questions that had 100% correct responses were "What is the most important treatment method in PKU?" and "When should the diet be started in PKU?" However, only 22.6% of the parents responded correctly to the questions on quantities of Phe in foods such as butter/margarine. The obtained results are in agreement with the data acquired in studies on mothers of children with PKU, which demonstrated poor parental dietary knowledge [12][13][14][15]. These results suggest that families may be more ignorant, especially on dietrelated issues. This may be due to a low perception of risk about the disease. In addition, our results also point to the gap in the training programs on PKU and its treatment. There is a need to develop interactive educational programs regarding the Phe content in foods as less than 50% of the parents knew the Phe content in the most commonly used foods, such as butter, vegetables, or fruit (Table 3). It is obvious that early diagnosis of PKU and adaptation to its diet as early as possible could prevent permanent brain damage, where patients could maintain a normal life and would have the chance to complete their school career [16]. This depends mostly on the quality of blood Phe control, which is influenced highly by the quantity and frequency of protein substitute administered, the amount of natural protein eaten, and the adequacy of energy intake from low Phe nutrients. However, in small children, all these factors are dependent on parental ability and discipline to continually apply this special dietary regimen. Naturally, the ability of parents to follow such a rigorous regime and treatment plan would be affected by various factors. Among all other factors, parents´ insufficient knowledge of the disease and lack of parental educational achievement appear to be important in overall blood Phe control [17,18].
Diets applied to patients with all metabolic diseases are difficult and require special attention. Parents who have children with PKU experience difficulties in learning and applying the required diet. All the parents do not have the same ability to learn the management of the diet; therefore, the nutritional treatment of the family should be arranged according to the socioeconomic status, educational learning desire, and diet therapy. Family support and the practical applications of PKU diet in training programs increase the success rate [10,12]. Therefore, the parents need not only training at the time of diagnosis but also support by continuous lifelong visual and practical training. Besides, the child´s growth rate and blood Phe level should also be monitored periodically [12]. Mostly, parents are trained during their routine visits to the hospital. As shown in our study, usually mothers are the ones who go to controls with the children, and naturally, it has been expected that mothers would have significantly higher knowledge of the disease and the diet than fathers. However, there was no statistically significant difference for KLS between the mothers and fathers who went to controls with their children. KLSs were higher among mothers in our study group.
In this study, 74% of the families stated that they had received some training on PKU and the restricted diet. This result shows the inadequacy of training because every mother and father must have a diet education, and this rate should be 100%. To comply with the treatment in PKU, cooperation among doctors, dieticians, nurses, patients´ family and relatives, and patients is required. Training should be done to evaluate the level of knowledge of patients and their relatives at different times [19,20]. Moreover, there is a need to form support groups and family therapy programs to overcome negative attitudes toward the PKU diet. This concerns the feeling of shame evoked by the necessity to follow a different diet. As mentioned by Rahgoi et al. [19] in a recent article, family-centered empowerment programs emphasizing an effective role of the family in the motivation, psychological growth, knowledge, attitudes, and perceived threats of the members can lead to health promotion.
In families with a child having a chronic illness, the care of the child and the workload of the hospital are mostly on the mother´s shoulders. This is not a cultural issue as Varni´s study [20] has shown that 80% of the parent forms were filled out by their mothers. As Raina et al. [21] reported that children with cerebral palsy are mostly nursed by their mothers, we understand that not only at the hospital but also at home, mothers undertake the major part of the sick child´s responsibility in all aspects of life. We have also seen that most of the children in our study were going to controls with their mothers (61.3%), and mothers gave more accurate answers to the questions on the specific diet regimen than fathers. Similarly, mothers´ KLSs were significantly higher than those of fathers. Therefore, the observed results are not surprising as mothers are more interested in their children´s diet and care. It should be emphasized that not only the mothers but also the fathers and/or other family members who care for the sick children should be taken into consideration when training programs are designed.
As mentioned before, the ability of parents to follow such a rigorous way would be affected by various factors. Our results revealed that the knowledge levels of the parents on PKU and its diet treatment decreased as the education level of the parents decreased. Similar to our results, Küçük Kasap [22] also observed a decrease in the dietary knowledge scores as the education level of the family decreased. Therefore, it would be appropriate to prepare the material to be used in the training programs according to the educational and cultural level of each family, and training should be continued until the trainers are sure that the family members fully understand the diet application. To control their diets in the adolescent period and to ensure their adaptation to dietary treatment, regular education programs on diseases and diets should be developed for parents and adolescents [14,15]. Durham-Shearer et al. reported that adolescent and adult patients with PKU are aware of their dietary recommendations and are compatible with the diet [23]. In our study, the highest KLSs were obtained among the parents whose children were 13 years of age or older. Naturally, the information gained about the disease increases over the years.
Limitations: our study has the following limitations. First, we analyzed the questionnaire results, and this does not reflect the main status of the patients. Second, these results belong to the limited geographic area in Turkey and could not be generalized for the whole country.

Conclusion
In conclusion, we observed that the level of knowledge of the parents about the disease and diet therapy is insufficient. To effectively care for PKU patients, special dietary attention and knowledge of the disease are required; otherwise, there will be a lot of negligence and error in treatment. For this reason, the patients and their family (both parents together) should be informed about the disease and diet therapy at specific intervals. Nutrition education should be provided to both parents according to the educational status and living conditions of the family. These trainings should be given by nutritionists who are trained primarily in metabolic diseases. This study confirms the need for professional actions to impart the practical knowledge of PKU nutrition to the family. Moreover, there is a need to form support groups and family therapy programs to overcome negative attitudes toward the PKU diet. This concerns the feeling of shame evoked by the necessity to follow a different diet.

What is known about this topic
 Newborn screening programs could identify the children with PKU as early as possible, and the most crucial consequence of the disease, mental motor retardation, could be prevented with appropriate treatment.  Table 1: characteristics of PKU patients and the attitudes of parents   7) What is the likelihood that a PKU carrier mother and father will be a PKU child again?